WO2022161820A1 - Machine de découpe laser - Google Patents

Machine de découpe laser Download PDF

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Publication number
WO2022161820A1
WO2022161820A1 PCT/EP2022/051068 EP2022051068W WO2022161820A1 WO 2022161820 A1 WO2022161820 A1 WO 2022161820A1 EP 2022051068 W EP2022051068 W EP 2022051068W WO 2022161820 A1 WO2022161820 A1 WO 2022161820A1
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WO
WIPO (PCT)
Prior art keywords
laser
nozzle
workpiece
cutting head
machining nozzle
Prior art date
Application number
PCT/EP2022/051068
Other languages
English (en)
Inventor
Colin Woratz
Original Assignee
Bystronic Laser Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bystronic Laser Ag filed Critical Bystronic Laser Ag
Publication of WO2022161820A1 publication Critical patent/WO2022161820A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/1462—Nozzles; Features related to nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/1462—Nozzles; Features related to nozzles
    • B23K26/1464—Supply to, or discharge from, nozzles of media, e.g. gas, powder, wire
    • B23K26/1476—Features inside the nozzle for feeding the fluid stream through the nozzle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/1462—Nozzles; Features related to nozzles
    • B23K26/1482—Detachable nozzles, e.g. exchangeable or provided with breakaway lines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/38—Removing material by boring or cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/70—Auxiliary operations or equipment
    • B23K26/702—Auxiliary equipment
    • B23K26/703—Cooling arrangements

Definitions

  • the invention is in the field of laser cutting of workpieces.
  • a directed laser beam moves relative to the metal workpiece to locally melt the metal material at the position of incidence of the laser beam on the workpiece. This produces a laser cut.
  • Modem laser cutting machines also direct a gas jet of an assist gas onto the position of incidence of the laser beam.
  • the gas jet may assist the removal (“blowing”) of molten metal material (fusion cutting) and/or, if it contains molecular oxygen, may be involved in a chemical reaction (“burning”; reactive cutting). Both, the removal and, if applicable, the chemical reaction, help to generate a good cutting kerf.
  • JP 2016/043392 discloses a laser cutting machine with an aperture the position of which is adjustable depending on the cutting mode.
  • JPH04-251688 discloses a laser beam machine with a condenser nozzle that comprises a condenser lens as well as an aperture immediately above or below the condenser lens.
  • the aperture has an acute-angle edge that acts as reflector for reflecting away peripheral, for example diffracted portions of the laser beam.
  • the condenser nozzle also has an inlet for assist gas that is supplied to the surface of the workpiece through the condenser nozzle.
  • the fact that the peripheral portions of the laser beam are cut off close to the focal point enhances the processing accuracy.
  • a disadvantage of this setup is that the cut-off peripheral portions are absorbed by the condenser nozzle, and this leads to a considerable heating of the condenser nozzle, including its optical system, especially the condenser lens.
  • a substantial heating of an optical lens leads to optical distortions and a reduced lifetime and is generally not acceptable.
  • WO 20137037825 and CH 682 060 disclose laser cutting machines with nozzles.
  • WO 20137037825 concerns a so-called universal nozzle that has a nozzle disc with several nozzle holes with different diameters.
  • the nozzle disc can be rotated to that the nozzle hole having a predetermined diameter can be rotated into a passage opening of the universal nozzle.
  • the nozzle diameter influences the amount and shape of the gas jet emitted onto the workpiece.
  • the nozzle of CH 682 060 is actively cooled by a cooling gas circulating in a channel to prevent the nozzle from being heated to a too high temperature by the thermal radiation emitted by the workpiece.
  • the laser cutting head has an interface for receiving laser radiation and defines a beam path. It may comprise a beam shaping installation, i.e., for example a focusing device (in this text ‘focusing device’ is to be understood to include any lens, curved mirror or combination of lens(es) and/or curved mirror(s) that collimates the laser beam and focuses it onto a desired position, for example close to the surface of the workpiece facing the laser cutting head.
  • the laser cutting head further has a laser machining nozzle through which the laser beam is directed onto the workpiece. The laser machining nozzle may be exchangeable.
  • the laser machining nozzle has a port for receiving a gas flow and has at least one gas channel for directing the gas flow onto the workpiece and thereby works as gas jet ejecting nozzle.
  • the nozzle also has an optical aperture for stopping (in other words: for cutting off) undesired marginal radiation portions (scattered radiation, marginal portions of the laser itself; “parasitic radiation”).
  • an optical aperture is provided by the laser machining nozzle itself - thus by the part that is closest to the workpiece.
  • laser machining nozzles are usually low-cost expendable items and are thus suitable for being exchanged between working cycles with different requirements to the laser beam. This yields a particularly simple possibility of adjusting laser beam properties without any sophisticated mechanics with additional moving parts: The laser beam properties may simply be adjusted by choosing and mounting the appropriate nozzle with the desired location and dimension of the optical aperture as well as desired nozzle dimensions.
  • the laser machining nozzle may be one-piece and may be of a suitable material, especially a metal. It is possible, though that the laser machining nozzle is compounded of several parts, which, however, may be separate from (i.e. not one-piece with) a cutting head body that may comprise a laser head housing.
  • the laser machining nozzle was designed such that any radiation absorption by the laser machining nozzle was avoided.
  • the present invention proposes to use the laser machining nozzle in a new way, by also using it as an optical aperture.
  • the shape of the laser beam is defined by the parameters of the laser source, the radiation conducting elements (especially the fiber leading from the laser source to the laser cutting head) and the focusing device in the laser cutting head.
  • the shape of the laser beam is hence a well-defined property of the laser cutting machine, possibly capable of being influenced within a certain defined range by focusing parameters.
  • the optical aperture is such as to cut off a marginal radiation portions of the laser beam.
  • the optical aperture on the one hand and the laser source and the other optical elements in the laser cutting head and coupled thereto are such that the optical aperture does have, for at least one choosable focusing parameter, an influence on the shape of the beam emitted from the nozzle.
  • the size of the nozzle opening is always chosen so that it is substantially larger than the diameter of the laser beam passing through the nozzle opening.
  • the optical aperture of the laser machining nozzle is an aperture stop of the laser cutting head, i.e. the aperture that defines the diameter of the laser beam at the position of incidence on the workpiece.
  • the laser machining nozzle is equipped to be cooled, especially by liquid cooling (water cooling).
  • it may comprise one or more cooling channels for a cooling liquid to circulate, as well as ports for injecting the cooling liquid and for discharging it.
  • the laser cutting head may comprise a cooled nozzle carrier carrying the nozzle and having a thermal contact with the nozzle.
  • a cooled nozzle carrier may comprise one or more cooling channels for a cooling liquid to circulate and ports for injecting the cooling liquid and to discharge it.
  • the cooling liquid may be cooling water or an other suitable cooling liquid.
  • the optical aperture may coincide with the nozzle workpiece- si de orifice through which the laser beam impinges on the workpiece.
  • the optical aperture may be at an axial distance therefrom, i.e., further away from the workpiece than the nozzle workpiece-side orifice (above it). This may be advantageous since due to physical contacts between the nozzle and the workpiece or burrs or debris etc., small damages may be caused at the workpiece-side of the nozzle during operation. If the aperture is not arranged there but at a distance therefrom, the properties of the laser beam will not be influenced by such damages.
  • the size of the optical aperture will be too small for the gas jet to be sufficiently strong. Therefore, the laser machining nozzle may in addition to the optical path define at least one gas channel that does not coincide with the beam channel through which the optical path goes, and that does not go through the optical aperture (this does not exclude that gas portions are caused to flow through the aperture in addition to the gas flowing through the separate gas channel or a side branch thereof which is separate from the beam channel).
  • the gas channel directs the assist gas through the gas channel onto a position of incidence of the laser beam onto the workpiece.
  • the at least one separate gas channel may have a gas ejection orifice (outlet opening) separate from a nozzle workpiece- si de orifice through which the laser beam impinges on the workpiece.
  • the gas channel may comprise a side branch that opens into the beam channel.
  • Such side branch may open into the beam channel especially on the workpiece-side of (closer to the workpiece than) the optical aperture.
  • the nozzle workpiece-side orifice through which both, the laser beam and the gas jet impinge on the workpiece may have a larger diameter than the optical aperture.
  • a diameter of the optical aperture may be, depending on the requirements, between 0.5 mm and 2.5 mm, for example between 0.6 mm and 1.5 mm, especially between 0.7 mm and 1.2 mm.
  • the workpiece-side orifice may, if it belongs to the gas channel, have a diameter of 1 mm to 2.5 mm or for certain applications may have a diameter of 1 mm to 10 mm.
  • the optical aperture will constitute the location of the beam channel across the laser cutting head at which the diameter is the smallest.
  • the laser cutting head also comprises a focusing device (focusing optics) that comprises a lens and/or a curved mirror.
  • focusing device focusing optics
  • the focusing device will be configured to focus the laser beam in a focal point on the workpiece, in the workpiece or near the workpiece (for example slightly above the workpiece). It may have an adjustable parameter so that the focal plane can be adjusted.
  • the focusing device in this is arranged remote from the nozzle, i.e. it is further above than the nozzle (referring to a beam path; more in general it is arranged in a manner that the beam is directed through the focusing device before it enters into the nozzle).
  • the element(s) of the focusing device is/are not in physical contact with the nozzle but is/are for example held by the cutting head body or a separate casing.
  • the focusing device is not in any physical contact with the nozzle and may the thermally de-coupled from the nozzle.
  • the laser cutting machine is thus free of any lenses or mirrors or other optical elements in physical contact with the laser machining nozzle. This construction makes possible that the optical aperture is used to stop the marginal radiation portions without any over-heating of optical elements, which over-heating would cause undesired distortions.
  • a distance between the element of the focusing device or, if the focusing device has more than one element, the one element that along the beam path is closest to the nozzle on the one hand and the nozzle on the other hand may be substantial, for example larger than an axial extension of the nozzle, for example at least 20 mm, at least 30 mm, or at least 40 mm.
  • the nozzle does not (directly) hold the focusing device or elements thereof, the focusing device will not be substantially heated even if the laser beam has a high power and/or if a comparably large portion of the radiation energy is cut off by the aperture.
  • High laser powers are especially important for a high cutting speed and for comparably thick workpieces, whereas the cutting off of a large portion may be beneficial for reactive cutting.
  • the approach according to the present invention according to which the nozzle having the double function of directing the gas jet onto the workpiece and serving for influencing the laser beam does not only allow the nozzle to be a passive low-cost part that may be readily exchangeable. It also has advantages in terms of achievable power and of the quality of the laser beam focusing.
  • the required laser beam properties may vary depending on the workpiece properties as well as on the nature of the cutting gas used (fusion cutting vs. reactive cutting).
  • the way the optical aperture interacts with the laser beam may be influenced.
  • One possibility to do so is to design the optical aperture as diaphragm with adjustable diameter.
  • the nozzle is usually an expendable item and also because cooling is an issue, in embodiments this is not the case. Rather, in embodiments the nozzle does not comprise any moving parts. Instead, other measures may be taken for influencing the interaction between the laser beam and the optical aperture.
  • the laser cutting head may be equipped for the relative position of the optical aperture and a focal position of the laser beam to be adjusted.
  • This may be achieved by the position of the laser machining nozzle being adjustable relative to a cutting head body, and/or by at least one optical element in the beam path having an adjustable position, for example a focusing lens.
  • This combination of an adjustment mechanism with the optical aperture of the laser machining nozzle has special advantages: On the one hand, it makes possible that the laser beam is provided as a uniform small-diameter beam for reactive cutting, by adjusting the parameters in a manner that only the core region of the laser beam goes through the optical aperture. Due to the small distance between the aperture and the workpiece, the resulting beam quality will be high.
  • the adjustment mechanism allows to convey more energy through the aperture by assuming a position in which also a more peripheral region of the laser beam is transmitted through the aperture, while other marginal portions, including side maxima and diffuse parasitic radiation (including scattered radiation) are still efficiently suppressed.
  • the nozzle - being exchangeable - may be present in different designs, with an external interface to the cutting head body (in particular to a nozzle carrier thereof) being the same for all designs. Between the designs one or more of the following may vary: A diameter of the optical aperture; an axial position of the optical aperture relative to the external interface; an overall axial dimension; a gas channel arrangement; a gas channel diameter; an outlet orifice diameter; etc. Therefore, in a kit of part that comprises the laser cutting head, especially with a nozzle carrier configured to receive the nozzle by way of a mechanical interface, there is further a plurality of differently designed nozzles all cooperating with the mechanical interface. In the differently designed nozzles, at least one of the above-mentioned properties may be different, especially the diameter of the optical aperture and/or the axial position of the optical aperture relative to the external interface and/or the axial extension.
  • the nozzle carrier (that may be part of the laser head body or a separate part) may be configured to receive the laser machining nozzle at a well-defined axial position relative to the laser head body so that the axial position of the optical aperture is defined by the structure of the laser machining nozzle.
  • the optical aperture may have a fix diameter, so that the laser machining nozzle does not have to comprise any moving parts (except for the whole laser machining nozzle being, in embodiments, movable relative to the cutting head body). This avoids a too complicated construction compared to the use of a diaphragm with adjustable diameter.
  • the laser cutting head may have a cutting head body that carries the interface and, if applicable, the beam shaping installation and at the workpiece side of which the laser machining nozzle is mounted, especially so as to be reversibly removable and exchangeable.
  • the present invention also concerns a method of operating a laser cutting machine, especially as described and claimed in the present text, the method comprising the steps of generating a laser beam, directing the laser beam, using a laser cutting head, onto a workpiece and at the same time ejecting, from a laser machining nozzle, a gas jet onto the workpiece, wherein the laser beam is directed through the laser machining nozzle.
  • the method further comprises using an optical aperture of the laser machining nozzle to stop marginal radiation portions of the laser beam.
  • the parameters of the laser source, of the radiation conductors (fibers) and of the focusing device are thus adapted to the dimensions of the nozzle such that the marginal portions of the beam (as described in the present text) are stopped by the optical aperture.
  • Fig. 1 A laser cutting machine
  • Figs. 2a, 2b A laser cutting head
  • Figs. 3 a, 3b An arrangement with the laser cutting head of Figs. 2a and 2band a workpiece;
  • Fig. 4 An alternative laser cutting head
  • Figs. 5a, 5b An arrangement with the laser cutting head of Fig. 4 and a workpiece;
  • Figs. 6a, 6b A nozzle in horizontal cross section close to the workpiece-side end thereof, and in vertical cross section, respectively;
  • Fig. 7 A further nozzle in vertical cross section; and Fig. 8 A part of a laser cutting head with an even further nozzle in vertical cross section.
  • FIG. 1 shows an example of a laser cutting machine 200.
  • the machine comprises a laser source 18 comprising a laser source module 18a and a transport fiber 18b, a laser cutting head 10, and a laser head moving mechanism.
  • a workpiece 12 is supported by a working table (not shown).
  • the laser cutting head moving mechanism comprises a bridge 202 relative to which the laser cutting head 100 is movable in x direction), and which itself is movable, for example on a pair or rails, in y direction relative to the working table and the workpiece 12.
  • the workpiece 12 may be a metal sheet that is cut by a laser beam emitted by the laser cutting head.
  • the workpiece may be a tube
  • the laser cutting machine may be a tube laser cutting machine
  • FIGS 2a and 2b schematically show an example of a laser cutting head 10.
  • the laser cutting head comprises an interface 14 for the laser source 18, a cutting head body 16 that contains a beam shaping installation for shaping the laser beam in a desired manner and, at a workpiece- si de end (the lower end in the depicted orientation in which the laser acts from above the workpiece 12), a nozzle 11, namely a laser machining nozzle.
  • the nozzle 11 is mounted in a slidable manner relative to a nozzle carrier 17 as explained in more detail hereinafter, so that a distance A between the nozzle workpiece-side orifice and an upper (upstream-most) end of the nozzle carrier may be varied for influencing the laser beam output on the workpiece.
  • the laser cutting head is illustrated to be symmetrical about its axis X, however, this is not a requirement.
  • Figures 3a and 3b depict the laser cutting head 10 with the laser source 18 coupled to the interface and with a drive 21 serving for moving the nozzle 11 the nozzle relative to the cutting head body 16, namely to the nozzle carrier 17 mounted fixedly to the cutting head body 16.
  • the relative position of the nozzle determines which regions of the laser beam get through the nozzle 11 and can impinge on the workpiece 12.
  • the laser beam 15 is illustrated to have, around a laser beam axis 15a (which in the depicted embodiment at least partly coincides with the laser cutting head axis illustrated in Fig. 2), a core region 15b of highest intensity and an outer region 15c comprising marginal beam portions. Even further outside, to-be-cut-off side maxima as well as scatter radiation (or parasitic radiation) may be present.
  • the nozzle 11 is positioned such as to block the outer region of the laser beam from being transmitted, so that only the core region 15b around the beam axis 15a gets onto the workpiece.
  • the core region 15b and the outer region 15c are directed onto the workpiece, due to the nozzle 11 being in a different position, whereas side maxima and scatter radiation are cut off also.
  • the laser beam is assumed to be convergent towards the workpiece 12, by means of a suitable focussing device, such as one or more focusing lenses 22. Then, the configuration in which the optical aperture formed by the nozzle 11 cuts off a larger portion of the laser beam 15 if it is in a relative position that is further away from the workpiece side (Fig. 3a) than if it is, more on the workpiece side relative to the cutting head body 16 (Fig.
  • the laser beam could also be divergent towards the workpiece. In such embodiments, if the laser beam diverges towards the workpiece at the position of the nozzle 11, then the opposite is true: the nozzle 11 cuts off a larger portion of the laser beam if it is further away from the workpiece.
  • Displacement of the nozzle relative position and/or of the focussing parameters may serve for a fine tuning of the aperture effect upon the laser beam.
  • fusion cutting on the one hand with some of the marginal beam portions being transmitted and only the more peripheral portions such as side maxima, and scatter radiation being cut off
  • reactive cutting on the other hand with more of the marginal beam portions being cut off
  • nozzles having different aperture diameters will be used.
  • Figure 3a also illustrates the distance d between the focusing device (focusing lens 22) on the one hand and the laser machining nozzle 11 on the other hand.
  • the distance d is the distance the light has to travel after passing the last element of the focusing device until it enters into the laser machining nozzle.
  • the distance d is greater than the axial extension (height in the depicted orientation) of the laser machining nozzle.
  • a displacement of the relative laser machining nozzle position will also change the distance d.
  • the distance will be greater than the axial extension of the laser machining nozzle for all choosable positions.
  • the laser machining nozzle is at a distance from the focusing device leads to a thermal de-coupling.
  • the focusing device (lens 22) is illustrated to be held by the cutting head body 16, and hence any heat absorbed by the (cooled) laser machining nozzle would have to be directed from the laser machining nozzle to the nozzle carrier 17, from there to the housing of the cutting head body and through the (usually relatively thin-walled) housing over the substantial distance d and from the housing to the focusing device 22.
  • Thermal radiation from the laser machining nozzle 11 to the focusing device is also a possible heating mechanism of the focusing device.
  • both, the thermal conduction through the housing and the thermal radiation are small, whereby the focusing device 22 is kept at a low temperature and is, for practical purposes, thermally de-coupled from the laser machining nozzle 11.
  • Figure 4 shows a variant of the laser cutting head, in which as an alternative to the nozzle being displaceable along the optical axis, or in addition thereto, a focusing element such as a focusing lens 22 is displaceable (arrow S).
  • Figures 5a and 5b schematically illustrate this principle with the outer region 15c of the laser beam being cut off (Fig. 5a) when the focusing lens 22 is at a first position, and with the outer region 15c of the laser reaching the surface of the workpiece 12 when the focusing lens 22 is at a second, different position.
  • an adjustment mechanism will comprise any mechanism for displacing the optical aperture formed by the nozzle and a laser focal point relative to one another, such as anyone or any combination of a drive for moving a focusing device relative to a cutting head body, a drive for moving the nozzle relative to a cutting head body, a device for moving the interface 14, etc.
  • the focusing device was assumed to belong, at least in part, to the laser cutting head.
  • the collimation optics is sometimes separated from the unit that is closest to the workpiece and carries the nozzle. It is then customary to designate only this unit closest to the workpiece as “laser cutting head” (or “cutting head”).
  • a collimation unit and for example a scanner unit (for Dynamic Beam Shaping (DBS)) is/are placed above the laser cutting head and move(s) with the laser cutting head.
  • a possibility to adjust the position of a focusing plane of the laser beam relative to the optical aperture by adjusting, relative to the collimation unit, an axial position of the entire laser cutting head that carries the nozzle. The effect is effectively the same as the one described referring to Figs.
  • the focusing device is not integrated in the cutting head body but separate therefrom, above it, and the position of the entire cutting head body (and not only the nozzle) and the focusing device/collimation unit being displaceable axially relative to one another, with the nozzle optionally being fixedly (but replaceably) mountable to the cutting head body.
  • Figure 6a shows a schematical horizontal section through an embodiment of nozzle at the workpiece-side end thereof
  • Figure 6b shows a schematical vertical section through the nozzle 11, together with a workpiece 12.
  • the diameter of the beam channel 31 is shown exaggerated for illustration purposes.
  • the nozzle has a plurality of (four in the depicted embodiment) gas channels 32 the diameter if which is sufficient for a sufficiently strong gas jet to be directed onto the workpiece. Further, the nozzle has at least one cooling channel 33 for a cooling liquid to flow through.
  • the optical aperture 34 consists of the upper (farthest away from the workpiece) end of the beam channel 31 in the nozzle. In embodiments of the kind shown in Figs. 6a and 6b with gas channels separate from the beam channel, however, the optical aperture could be located anywhere along the beam channel in the nozzle, including at its workpiece-side end. Since the beam channel in the nozzle is relatively short compared to the dimension of the whole laser cutting head 10, the exact axial position of the optical aperture within the nozzle does not even have to be exactly defined and can for example be constituted by the entire nozzle.
  • the diameter d a of the aperture will depend on the requirements and will be between 0.3 mm and 3 mm, especially between 0.5 mm and about 1.5 mm.
  • An axial extension a of the nozzle (or of the beam channel in the nozzle) may be around 8 mm - 70 mm, for example between 10 mm and 60 mm or between 15 mm and 40 mm.
  • the diameter d of the nozzle may for example be at least 10 mm and may be as high as possible due to the circumstances, for example between 10 mm and 80 mm.
  • Figure 7 shows an alternative embodiment in which the gas jet is ejected onto the workpiece from the same orifice as the laser beam, i.e., in which the nozzle workpieceside orifice 13 also belongs to the gas channel 32.
  • the gas channel 32 comprises a separate side branch that opens into the beam channel 31 and is connected to a gas supply port 35. The location at which the side branch opens into the beam channel 31 in this may be on the workpiece-side from the optical aperture 34.
  • the optical aperture 34 is again constituted by the upper (away from the workpiece-side) end of the nozzle 11.
  • the nozzle has, with the exception of the gas channel(s) and the cooling channel(s), a circular symmetry around its axis, which in the nozzle may coincide with the laser beam axis. It is possible, however, that one deviates from such symmetry, for example by designing the nozzle outlet opening 13 in a non-round shape so as to optimize the gas flow therethrough.
  • the aperture itself is non-round, whereas for most embodiments, to ensure a uniform cut thickness, the laser beam, and therefore also the aperture, may have a round cross section.
  • Figure 8 shows a nozzle based on the principle of the principle described referring to Fig. 7 together with a nozzle carrier 17.
  • the nozzle is not directly cooled, i.e. it does not have any cooling channels. Rather, the cooling is indirectly by the nozzle carrier having a cooling channel, and by the nozzle 11 being secured to the nozzle carrier - which itself is of a material that is a good thermal conductor, such as a suitable metal - by a good thermal contact.
  • this thermal contact on the one hand is established by a planar surface portion 42 of the nozzle 11 abutting against a corresponding surface portion of the nozzle carrier 17.
  • an outer thread 41 cooperating with a corresponding inner thread of the nozzle carrier is a good thermal conductor.
  • connection between the nozzle 11 and the nozzle carrier 17 is a screwed connection. Moreover, the thermal contact is complete only if the planar surface portion 42 abuts against the corresponding plane of the nozzle carrier, whereby the relative axial position of the nozzle carrier 17 and the nozzle 11 is defined and cannot be adjusted. If the axial position of the aperture 34 - or its diameter - is to be changed, this can be done by exchanging the nozzle 11 that in embodiments like the one of Fig. 8, by not having any cooling channels and thus not requiring any according port etc. - is of a particularly simple design and can be used as a low-cost expendable item.
  • a kit of parts may comprise in addition to the cutting head body 16 that has the nozzle carrier 17, a plurality of nozzles, for example of different dimensions, aperture sizes and/or aperture axial positions.
  • the effect of the aperture 34 could in addition be fine tuned by a combination of varying the distance between the laser cutting head (carrying the nozzle 11) and the workpiece and also of the focal position so that effectively the beam is moved relative to the nozzle 11 having the aperture 34.
  • the nozzle may also be mounted to be displaceable also in embodiments with indirect cooling.
  • the parts may be dimensioned for the thermal contact via a thread (or similar) to be sufficient, to have a spring-loaded thermal contact, or any other suitable means.
  • the nozzle may also be fastened by other means, including a plugged connection, a snap-on mounting, a bayonet coupling, a separate fastener (such as a screw r the like), etc.
  • the nozzle is illustrated to comprise gas supply port 35 for a gas conduit (hose or the like) to be coupled thereto.
  • the nozzle carrier may comprise a nozzle carrier gas conduit and the nozzle carrier and the nozzle may comprise a gas coupling, whereby the gas is supplied to the nozzle’s gas channel via the nozzle carrier.
  • the gas channel may be at least partially separate from the beam channel, i.e., it may have a separate orifice (in analogy to the configuration of Fig. 6b) or a may have a side branch opening into the beam channel (like in the configuration of Fig. 7).
  • Fig. 8 in addition to the features discussed above also illustrates the principle that it is an option that the beam properties of the laser beam may be adjusted by choosing and mounting the appropriate nozzle 11 out of a choice of different nozzles.
  • the optical aperture 34 is illustrated to be relatively small and relatively close to the focusing lens 22 such as to cut off the outer region 15c of the laser beam. By choosing a nozzle with an optical aperture of different size or of a different axial position, this may be changed.
  • the inner thread of the nozzle carrier serves as mechanical interface for receiving the different nozzles of different designs (but with identical outer thread 41 and planar surface portion 42).

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

La présente invention concerne une tête de découpe laser qui présente une interface destinée à recevoir un rayonnement laser et qui définit un trajet de faisceau. La tête de découpe laser comprend en outre une buse d'usinage laser (11) à travers laquelle le faisceau laser est dirigé sur la pièce à usiner (12). La buse d'usinage laser peut être interchangeable. Elle est disposée sur un côté de la pièce à usiner de la tête de découpe laser. La buse d'usinage laser comporte un orifice (35) destiné à recevoir un flux de gaz et présente au moins un canal de gaz (32) destiné à diriger le flux de gaz sur la pièce à usiner (12) et fonctionne ainsi en tant que buse d'éjection de jet de gaz. Selon un aspect de la présente invention, la buse présente également une ouverture optique (34) destinée à des parties de rayonnement marginal.
PCT/EP2022/051068 2021-01-29 2022-01-19 Machine de découpe laser WO2022161820A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21154344.2A EP4035822A1 (fr) 2021-01-29 2021-01-29 Machine de découpe au laser
EP21154344.2 2021-01-29

Publications (1)

Publication Number Publication Date
WO2022161820A1 true WO2022161820A1 (fr) 2022-08-04

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WO (1) WO2022161820A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116441759B (zh) * 2023-06-17 2023-09-01 南宫市罗康毛毡有限公司 高散热激光切割机

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04251688A (ja) * 1991-01-23 1992-09-08 Fanuc Ltd レーザ加工機
CH682060A5 (fr) * 1987-05-18 1993-07-15 Weidmueller C A Gmbh Co
US5786561A (en) * 1994-01-25 1998-07-28 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Nozzle assembly for laser beam cutting
JP3418462B2 (ja) * 1994-08-26 2003-06-23 株式会社ダイヘン レ−ザ加工ト−チ
US20030192865A1 (en) * 2002-04-16 2003-10-16 W.A. Whitney Co. Method and apparatus for laser piercing and cutting metal sheet and plate
WO2013037825A1 (fr) 2011-09-14 2013-03-21 Trumpf Werkzeugmaschinen Gmbh + Co. Kg Buse universelle pour machine de découpe au laser et procédé pour régler la buse universelle dans une machine de découpe au laser
JP2016043392A (ja) 2014-08-25 2016-04-04 株式会社アマダホールディングス レーザ加工機及びレーザ切断加工方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH682060A5 (fr) * 1987-05-18 1993-07-15 Weidmueller C A Gmbh Co
JPH04251688A (ja) * 1991-01-23 1992-09-08 Fanuc Ltd レーザ加工機
US5786561A (en) * 1994-01-25 1998-07-28 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Nozzle assembly for laser beam cutting
JP3418462B2 (ja) * 1994-08-26 2003-06-23 株式会社ダイヘン レ−ザ加工ト−チ
US20030192865A1 (en) * 2002-04-16 2003-10-16 W.A. Whitney Co. Method and apparatus for laser piercing and cutting metal sheet and plate
WO2013037825A1 (fr) 2011-09-14 2013-03-21 Trumpf Werkzeugmaschinen Gmbh + Co. Kg Buse universelle pour machine de découpe au laser et procédé pour régler la buse universelle dans une machine de découpe au laser
JP2016043392A (ja) 2014-08-25 2016-04-04 株式会社アマダホールディングス レーザ加工機及びレーザ切断加工方法

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